Deep bite, commonly referred to as an overbite, is one of the most common dental malocclusions. In patients who have deep bite, the lower front teeth (mandibular anteriors) close deep behind the upper front teeth (maxillary anteriors). This condition causes a number of problems. Because the lower front teeth do not close in alignment with the upper front teeth, the lower jaw (mandible) closes too far up, i.e. autorotates up, or comes too close to the upper jaw. This is usually due to extra pressure on the back teeth, which causes them to recede (intrude) into the gum, or to never fully erupt properly, or to be ground down, bruxed or worn. (It may also be due to missing posterior teeth, due to caries or periodontal problems.) The further the back teeth recede (intrude) into the gum the more the lower front teeth undercut the upper front teeth. As the lower front teeth cut higher behind the upper front teeth, they are pushed back, along with the lower jaw, because the backs of the upper front teeth are thicker at their base (at the gum line) than at their incisal edge. The top front teeth are sometimes pushed forward and are spaced apart. As a result, there is less space in this inter-canine region, causing the lower front teeth to crowd in order to fit there. In addition to creating an ineffective bite, the misalignment of the lower front teeth behind the upper front teeth can cause crowding of the lower teeth as they are pushed back by the upper front teeth. Because the misalignment also forces the mandible toward the back of the head, these forces can result in painful conditions of the temporomandibular joint, called TMJ or TMD.
Deep bite can arise for many reasons, the most common being nocturnal, and occasionally waking, clenching and grinding (bruxism) of the teeth, which both wears down and intrudes the back teeth. Accidents and loss of rear teeth due to decay and periodontal problems can also cause deep bite.
Corrective measures for deep bite aim to “open” the bite, by preventing the lower jaw from closing as close to the upper jaw, and stopping the negative effects of the clenching and grinding of the teeth. As the lower jaw is not closed so tightly and the lower front teeth are not forced backward by the backs of the upper front teeth, the condition can be gradually corrected in that the back teeth, which have been relieved of the pressure of closing on each other, are now able to extrude out of the jaw. Once the back teeth have extruded sufficiently that the lower front teeth are no longer closing on the inward sloping back of the upper front teeth, rearward pressure on the lower jaw is relieved.
Deep bite has been treated for many years by installing in the roof of the mouth a bite plate, also termed a retainer. The bite plate is a custom-made device modeled on a casting of the patient's teeth. The bite plate, which is removable, attaches to the upper teeth with wires shaped to fit the outside of the upper front and back teeth. The device also has a plastic component shaped to fit the roof of the patient's mouth. Together, the wires and the plastic component hold the bite plate in the patient's mouth. The plastic portion of the bite plate extends forward from the roof of the mouth to just behind the upper front teeth. As such, the plastic portion blocks the lower front teeth from closing too far up and behind the upper front teeth. Instead of hitting the backs of the upper front teeth, the lower front teeth hit the plastic part of the bite plate (the anterior bite plane). Because the back teeth are now not closing as fully or tightly as without the plate, they are able to gradually extrude. Also, because the lower front teeth are not closing so far up, they are not pressed as tightly behind the upper front teeth, and there is less cause for crowding of the lower front teeth. Lastly, since the pressure of the bite is now vertically on the smaller lower front teeth mostly, it sends the brain the message to stop clenching so much.
Bite plates are not without problems, however. Being custom made, requiring a mold of the patient's teeth and a poured model, they are costly to make and replace, and because they are removable, are occasionally broken and lost, especially by younger patients. Moreover, because the wire retainer is formed on a casting of the teeth in their uncorrected state, the retainer inhibits or complicates any corrective adjustment while it is being worn, which makes corrective adjustment more difficult.
Another, less common, treatment for deep bite involves the bonding of small blocking devices directly to the back of the upper front teeth. These devices, termed lingual bite blocks, buttons, bite ramps, or Bite Turbos™, function similarly as bite plates in that they prevent the lower front teeth from pressing up against the inside of the upper front teeth. Anthony in U.S. Pat. No. 5,957,686 and Lotte in U.S. Pat. No. 6,364,659 describe two such devices. Lingual bite blocks or buttons can cause chipping of the lower teeth, and occasionally come off, which can be highly dangerous if they are aspirated. Additionally, they too can be expensive, require a model, and are custom made to fit the shape of the patients lingual tooth surface.